textproduct: Rapid City

KEY MESSAGES

- Isolated severe storm threat Saturday, mainly over northeast WY and southwest SD.

- Beneficial rainfall expected Saturday into Sunday.

- Cooler temperatures for Sunday through Tuesday, then a gradual warm up for the rest of next week.

DISCUSSION

(This Evening Through Friday) Issued at 144 PM MDT Fri Jun 19 2026

Current upper-air analysis and water vapor imagery depict weak troughing over the Great Lakes region and split flow off the west coast. The shortwave that produced thunderstorms over portions of the region last night has moved off to the east, leaving partly cloudy skies across western/central South Dakota. Surface observations show temperatures mainly in the 60s to low 70s, with dew points in the upper 30s to low 40s across northeast WY and 40s to low 50s across western SD. Winds are generally northwesterly at 20kts gusting to 35kts across northwest SD, while winds across southwest SD into northeast WY are more northerly/northeasterly at 15kts gusting to 25kts.

Today will be mostly dry as the shortwave continues to move off to the east, leading to high temperatures mainly in the 70s to low 80s over the plains and 60s for the Black Hills. Winds will remain gusty through the afternoon before transitioning to a south/southeasterly flow late tonight. Elevated fire weather conditions will be present today due to the gusty winds in combination with the lower RH values, especially over northeast WY.

Saturday is expected to be more unsettled as a shortwave moves in the region from the southern steam of the split flow. SPC currently has northeast WY, the Black Hills, and southwest SD in a marginal risk, with a slight risk in the far southern portions of Fall River and Oglala Lakota counties. With the generally southerly flow developing tonight, dew points look to increase into the low 50s Saturday morning across northeast WY (~40 to 55% chance, 12z HREF) and southwest SD (~75 to 90% chance, 12z HREF). Mean surface-based CAPE values look to be on the low to moderate side at ~700 to 900 J/kg (12z HREF) for the late morning/early afternoon for northeast WY. 0-6km wind shear is leaning towards moderate levels over northeast WY, with the HREF showing values ranging between 30 to 45kts for the early afternoon. Storms are expected to form over northeast WY during the early afternoon and again later in the evening; however, with marginal dew points and shear values on the edge for supercell development, the likelihood for severe weather remains uncertain for much of the region. The better chance for severe weather will be for east-central WY into the NE panhandle, where dew points will be higher and shear values will be more consistent.

Showers and storms will linger into Sunday, providing much-needed rainfall across the region. QPF values are trending towards at least 0.50" for most locations, with higher amounts east of the Black Hills, where 1.00" to 1.50" is not out of the question. If guidance continues to trend in this direction, this weekend will prove very beneficial for the region. Unsettled weather is expected to continue into the week ahead, with precipitation chances possible on most days. Cooler temperatures will be present to start off the week, will a gradual warm up for the rest of the week.

AVIATION

(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 500 PM MDT Fri Jun 19 2026

Mainly VFR conditions are expected through the forecast period. Isolated showers after 20/03z may occur with increasing chances for shra/TS through the day Saturday. Any thunderstorm may contain local IFR conditions.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.